Bug 4564: Implement GetSnapshot message in RaftActor
[controller.git] / opendaylight / md-sal / sal-akka-raft / src / main / java / org / opendaylight / controller / cluster / raft / RaftActor.java
index 1c30fe23175b5af62ffe808d9428c3361688a4b0..5f6f3ec24e573c4dedba6ba42a38dbbe28a51698 100644 (file)
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
+ * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
@@ -11,22 +12,18 @@ package org.opendaylight.controller.cluster.raft;
 import akka.actor.ActorRef;
 import akka.actor.ActorSelection;
 import akka.japi.Procedure;
-import akka.persistence.RecoveryCompleted;
-import akka.persistence.SaveSnapshotFailure;
-import akka.persistence.SaveSnapshotSuccess;
-import akka.persistence.SnapshotOffer;
-import akka.persistence.SnapshotSelectionCriteria;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Objects;
 import com.google.common.base.Optional;
-import com.google.common.base.Stopwatch;
-import com.google.common.collect.ImmutableMap;
+import com.google.common.base.Supplier;
 import com.google.common.collect.Lists;
 import java.io.Serializable;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.Nonnull;
 import org.apache.commons.lang3.time.DurationFormatUtils;
 import org.opendaylight.controller.cluster.DataPersistenceProvider;
 import org.opendaylight.controller.cluster.DelegatingPersistentDataProvider;
@@ -36,12 +33,10 @@ import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersisten
 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
 import org.opendaylight.controller.cluster.notifications.RoleChanged;
 import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplyLogEntries;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
 import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
-import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
-import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshotReply;
+import org.opendaylight.controller.cluster.raft.base.messages.InitiateCaptureSnapshot;
 import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
+import org.opendaylight.controller.cluster.raft.base.messages.SwitchBehavior;
 import org.opendaylight.controller.cluster.raft.behaviors.AbstractLeader;
 import org.opendaylight.controller.cluster.raft.behaviors.DelegatingRaftActorBehavior;
 import org.opendaylight.controller.cluster.raft.behaviors.Follower;
@@ -99,8 +94,6 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
 
     private static final long APPLY_STATE_DELAY_THRESHOLD_IN_NANOS = TimeUnit.MILLISECONDS.toNanos(50L); // 50 millis
 
-    private static final String COMMIT_SNAPSHOT = "commit_snapshot";
-
     protected final Logger LOG = LoggerFactory.getLogger(getClass());
 
     /**
@@ -115,35 +108,34 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
      */
     private final RaftActorContextImpl context;
 
-    private final DelegatingPersistentDataProvider delegatingPersistenceProvider = new DelegatingPersistentDataProvider(null);
+    private final DelegatingPersistentDataProvider delegatingPersistenceProvider;
 
-    private final Procedure<Void> createSnapshotProcedure = new CreateSnapshotProcedure();
+    private final PersistentDataProvider persistentProvider;
 
-    private Stopwatch recoveryTimer;
+    private RaftActorRecoverySupport raftRecovery;
 
-    private int currentRecoveryBatchCount;
+    private RaftActorSnapshotMessageSupport snapshotSupport;
 
     private final BehaviorStateHolder reusableBehaviorStateHolder = new BehaviorStateHolder();
 
-    public RaftActor(String id, Map<String, String> peerAddresses) {
-        this(id, peerAddresses, Optional.<ConfigParams>absent());
-    }
+    private final SwitchBehaviorSupplier reusableSwitchBehaviorSupplier = new SwitchBehaviorSupplier();
+
+    private RaftActorServerConfigurationSupport serverConfigurationSupport;
 
     public RaftActor(String id, Map<String, String> peerAddresses,
-         Optional<ConfigParams> configParams) {
+         Optional<ConfigParams> configParams, short payloadVersion) {
+
+        persistentProvider = new PersistentDataProvider(this);
+        delegatingPersistenceProvider = new RaftActorDelegatingPersistentDataProvider(null, persistentProvider);
 
         context = new RaftActorContextImpl(this.getSelf(),
-            this.getContext(), id, new ElectionTermImpl(delegatingPersistenceProvider, id, LOG),
+            this.getContext(), id, new ElectionTermImpl(persistentProvider, id, LOG),
             -1, -1, peerAddresses,
-            (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()), LOG);
+            (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
+            delegatingPersistenceProvider, LOG);
 
-        context.setReplicatedLog(ReplicatedLogImpl.newInstance(context, delegatingPersistenceProvider, currentBehavior));
-    }
-
-    private void initRecoveryTimer() {
-        if(recoveryTimer == null) {
-            recoveryTimer = Stopwatch.createStarted();
-        }
+        context.setPayloadVersion(payloadVersion);
+        context.setReplicatedLog(ReplicatedLogImpl.newInstance(context, currentBehavior));
     }
 
     @Override
@@ -152,11 +144,14 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
                 context.getConfigParams().getJournalRecoveryLogBatchSize());
 
         super.preStart();
+
+        snapshotSupport = newRaftActorSnapshotMessageSupport();
+        serverConfigurationSupport = new RaftActorServerConfigurationSupport(getRaftActorContext());
     }
 
     @Override
     public void postStop() {
-        if(currentBehavior != null) {
+        if(currentBehavior.getDelegate() != null) {
             try {
                 currentBehavior.close();
             } catch (Exception e) {
@@ -169,134 +164,29 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
 
     @Override
     public void handleRecover(Object message) {
-        if(persistence().isRecoveryApplicable()) {
-            if (message instanceof SnapshotOffer) {
-                onRecoveredSnapshot((SnapshotOffer) message);
-            } else if (message instanceof ReplicatedLogEntry) {
-                onRecoveredJournalLogEntry((ReplicatedLogEntry) message);
-            } else if (message instanceof ApplyLogEntries) {
-                // Handle this message for backwards compatibility with pre-Lithium versions.
-                onRecoveredApplyLogEntries(((ApplyLogEntries) message).getToIndex());
-            } else if (message instanceof ApplyJournalEntries) {
-                onRecoveredApplyLogEntries(((ApplyJournalEntries) message).getToIndex());
-            } else if (message instanceof DeleteEntries) {
-                replicatedLog().removeFrom(((DeleteEntries) message).getFromIndex());
-            } else if (message instanceof UpdateElectionTerm) {
-                context.getTermInformation().update(((UpdateElectionTerm) message).getCurrentTerm(),
-                        ((UpdateElectionTerm) message).getVotedFor());
-            } else if (message instanceof RecoveryCompleted) {
-                onRecoveryCompletedMessage();
-            }
-        } else {
-            if (message instanceof RecoveryCompleted) {
-                // Delete all the messages from the akka journal so that we do not end up with consistency issues
-                // Note I am not using the dataPersistenceProvider and directly using the akka api here
-                deleteMessages(lastSequenceNr());
-
-                // Delete all the akka snapshots as they will not be needed
-                deleteSnapshots(new SnapshotSelectionCriteria(scala.Long.MaxValue(), scala.Long.MaxValue()));
-
-                onRecoveryComplete();
-
-                initializeBehavior();
-            }
-        }
-    }
-
-    private void onRecoveredSnapshot(SnapshotOffer offer) {
-        if(LOG.isDebugEnabled()) {
-            LOG.debug("{}: SnapshotOffer called..", persistenceId());
-        }
-
-        initRecoveryTimer();
-
-        Snapshot snapshot = (Snapshot) offer.snapshot();
-
-        // Create a replicated log with the snapshot information
-        // The replicated log can be used later on to retrieve this snapshot
-        // when we need to install it on a peer
-
-        context.setReplicatedLog(ReplicatedLogImpl.newInstance(snapshot, context, delegatingPersistenceProvider,
-                currentBehavior));
-        context.setLastApplied(snapshot.getLastAppliedIndex());
-        context.setCommitIndex(snapshot.getLastAppliedIndex());
-
-        Stopwatch timer = Stopwatch.createStarted();
-
-        // Apply the snapshot to the actors state
-        applyRecoverySnapshot(snapshot.getState());
-
-        timer.stop();
-        LOG.info("Recovery snapshot applied for {} in {}: snapshotIndex={}, snapshotTerm={}, journal-size=" +
-                replicatedLog().size(), persistenceId(), timer.toString(),
-                replicatedLog().getSnapshotIndex(), replicatedLog().getSnapshotTerm());
-    }
-
-    private void onRecoveredJournalLogEntry(ReplicatedLogEntry logEntry) {
-        if(LOG.isDebugEnabled()) {
-            LOG.debug("{}: Received ReplicatedLogEntry for recovery: {}", persistenceId(), logEntry.getIndex());
-        }
-
-        replicatedLog().append(logEntry);
-    }
-
-    private void onRecoveredApplyLogEntries(long toIndex) {
-        if(LOG.isDebugEnabled()) {
-            LOG.debug("{}: Received ApplyLogEntries for recovery, applying to state: {} to {}",
-                    persistenceId(), context.getLastApplied() + 1, toIndex);
+        if(raftRecovery == null) {
+            raftRecovery = newRaftActorRecoverySupport();
         }
 
-        for (long i = context.getLastApplied() + 1; i <= toIndex; i++) {
-            batchRecoveredLogEntry(replicatedLog().get(i));
-        }
-
-        context.setLastApplied(toIndex);
-        context.setCommitIndex(toIndex);
-    }
+        boolean recoveryComplete = raftRecovery.handleRecoveryMessage(message, persistentProvider);
+        if(recoveryComplete) {
+            onRecoveryComplete();
 
-    private void batchRecoveredLogEntry(ReplicatedLogEntry logEntry) {
-        initRecoveryTimer();
-
-        int batchSize = context.getConfigParams().getJournalRecoveryLogBatchSize();
-        if(currentRecoveryBatchCount == 0) {
-            startLogRecoveryBatch(batchSize);
-        }
+            initializeBehavior();
 
-        appendRecoveredLogEntry(logEntry.getData());
+            raftRecovery = null;
 
-        if(++currentRecoveryBatchCount >= batchSize) {
-            endCurrentLogRecoveryBatch();
+            if (context.getReplicatedLog().size() > 0) {
+                self().tell(new InitiateCaptureSnapshot(), self());
+                LOG.info("Snapshot capture initiated after recovery");
+            } else {
+                LOG.info("Snapshot capture NOT initiated after recovery, journal empty");
+            }
         }
     }
 
-    private void endCurrentLogRecoveryBatch() {
-        applyCurrentLogRecoveryBatch();
-        currentRecoveryBatchCount = 0;
-    }
-
-    private void onRecoveryCompletedMessage() {
-        if(currentRecoveryBatchCount > 0) {
-            endCurrentLogRecoveryBatch();
-        }
-
-        onRecoveryComplete();
-
-        String recoveryTime = "";
-        if(recoveryTimer != null) {
-            recoveryTimer.stop();
-            recoveryTime = " in " + recoveryTimer.toString();
-            recoveryTimer = null;
-        }
-
-        LOG.info(
-            "Recovery completed" + recoveryTime + " - Switching actor to Follower - " +
-                "Persistence Id =  " + persistenceId() +
-                " Last index in log={}, snapshotIndex={}, snapshotTerm={}, " +
-                "journal-size={}",
-            replicatedLog().lastIndex(), replicatedLog().getSnapshotIndex(),
-            replicatedLog().getSnapshotTerm(), replicatedLog().size());
-
-        initializeBehavior();
+    protected RaftActorRecoverySupport newRaftActorRecoverySupport() {
+        return new RaftActorRecoverySupport(context, currentBehavior, getRaftActorRecoveryCohort());
     }
 
     protected void initializeBehavior(){
@@ -309,8 +199,11 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
     }
 
-    @Override public void handleCommand(Object message) {
-        if (message instanceof ApplyState){
+    @Override
+    public void handleCommand(final Object message) {
+        if(serverConfigurationSupport.handleMessage(message, this, getSender())) {
+            return;
+        } else if (message instanceof ApplyState){
             ApplyState applyState = (ApplyState) message;
 
             long elapsedTime = (System.nanoTime() - applyState.getStartTime());
@@ -328,6 +221,16 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
             applyState(applyState.getClientActor(), applyState.getIdentifier(),
                 applyState.getReplicatedLogEntry().getData());
 
+            if (!hasFollowers()) {
+                // for single node, the capture should happen after the apply state
+                // as we delete messages from the persistent journal which have made it to the snapshot
+                // capturing the snapshot before applying makes the persistent journal and snapshot out of sync
+                // and recovery shows data missing
+                context.getReplicatedLog().captureSnapshotIfReady(applyState.getReplicatedLogEntry());
+
+                context.getSnapshotManager().trimLog(context.getLastApplied(), currentBehavior);
+            }
+
         } else if (message instanceof ApplyJournalEntries){
             ApplyJournalEntries applyEntries = (ApplyJournalEntries) message;
             if(LOG.isDebugEnabled()) {
@@ -336,68 +239,55 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
 
             persistence().persist(applyEntries, NoopProcedure.instance());
 
-        } else if(message instanceof ApplySnapshot ) {
-            Snapshot snapshot = ((ApplySnapshot) message).getSnapshot();
-
-            if(LOG.isDebugEnabled()) {
-                LOG.debug("{}: ApplySnapshot called on Follower Actor " +
-                        "snapshotIndex:{}, snapshotTerm:{}", persistenceId(), snapshot.getLastAppliedIndex(),
-                    snapshot.getLastAppliedTerm()
-                );
-            }
-
-            applySnapshot(snapshot.getState());
-
-            //clears the followers log, sets the snapshot index to ensure adjusted-index works
-            context.setReplicatedLog(ReplicatedLogImpl.newInstance(snapshot, context, delegatingPersistenceProvider,
-                    currentBehavior));
-            context.setLastApplied(snapshot.getLastAppliedIndex());
-
         } else if (message instanceof FindLeader) {
             getSender().tell(
                 new FindLeaderReply(getLeaderAddress()),
                 getSelf()
             );
-
-        } else if (message instanceof SaveSnapshotSuccess) {
-            SaveSnapshotSuccess success = (SaveSnapshotSuccess) message;
-            LOG.info("{}: SaveSnapshotSuccess received for snapshot", persistenceId());
-
-            long sequenceNumber = success.metadata().sequenceNr();
-
-            commitSnapshot(sequenceNumber);
-
-        } else if (message instanceof SaveSnapshotFailure) {
-            SaveSnapshotFailure saveSnapshotFailure = (SaveSnapshotFailure) message;
-
-            LOG.error("{}: SaveSnapshotFailure received for snapshot Cause:",
-                    persistenceId(), saveSnapshotFailure.cause());
-
-            context.getSnapshotManager().rollback();
-
-        } else if (message instanceof CaptureSnapshot) {
-            LOG.debug("{}: CaptureSnapshot received by actor: {}", persistenceId(), message);
-
-            context.getSnapshotManager().create(createSnapshotProcedure);
-
-        } else if (message instanceof CaptureSnapshotReply) {
-            handleCaptureSnapshotReply(((CaptureSnapshotReply) message).getSnapshot());
         } else if(message instanceof GetOnDemandRaftState) {
             onGetOnDemandRaftStats();
-        } else if (message.equals(COMMIT_SNAPSHOT)) {
-            commitSnapshot(-1);
-        } else {
-            reusableBehaviorStateHolder.init(getCurrentBehavior());
+        } else if(message instanceof InitiateCaptureSnapshot) {
+            captureSnapshot();
+        } else if(message instanceof SwitchBehavior){
+            switchBehavior(((SwitchBehavior) message));
+        } else if(!snapshotSupport.handleSnapshotMessage(message, getSender())) {
+            switchBehavior(reusableSwitchBehaviorSupplier.handleMessage(getSender(), message));
+        }
+    }
+
+    private void switchBehavior(SwitchBehavior message) {
+        if(!getRaftActorContext().getRaftPolicy().automaticElectionsEnabled()) {
+            RaftState newState = message.getNewState();
+            if( newState == RaftState.Leader || newState == RaftState.Follower) {
+                switchBehavior(reusableSwitchBehaviorSupplier.handleMessage(getSender(), message));
+                getRaftActorContext().getTermInformation().updateAndPersist(message.getNewTerm(), "");
+            } else {
+                LOG.warn("Switching to behavior : {} - not supported", newState);
+            }
+        }
+    }
 
-            setCurrentBehavior(currentBehavior.handleMessage(getSender(), message));
+    private void switchBehavior(Supplier<RaftActorBehavior> supplier){
+        reusableBehaviorStateHolder.init(getCurrentBehavior());
 
-            handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
-        }
+        setCurrentBehavior(supplier.get());
+
+        handleBehaviorChange(reusableBehaviorStateHolder, getCurrentBehavior());
+    }
+
+    protected RaftActorSnapshotMessageSupport newRaftActorSnapshotMessageSupport() {
+        return new RaftActorSnapshotMessageSupport(context, currentBehavior,
+                getRaftActorSnapshotCohort());
     }
 
     private void onGetOnDemandRaftStats() {
         // Debugging message to retrieve raft stats.
 
+        Map<String, String> peerAddresses = new HashMap<>();
+        for(String peerId: context.getPeerIds()) {
+            peerAddresses.put(peerId, context.getPeerAddress(peerId));
+        }
+
         OnDemandRaftState.Builder builder = OnDemandRaftState.builder()
                 .commitIndex(context.getCommitIndex())
                 .currentTerm(context.getTermInformation().getCurrentTerm())
@@ -413,7 +303,7 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
                 .snapshotIndex(replicatedLog().getSnapshotIndex())
                 .snapshotTerm(replicatedLog().getSnapshotTerm())
                 .votedFor(context.getTermInformation().getVotedFor())
-                .peerAddresses(ImmutableMap.copyOf(context.getPeerAddresses()));
+                .peerAddresses(peerAddresses);
 
         ReplicatedLogEntry lastLogEntry = getLastLogEntry();
         if (lastLogEntry != null) {
@@ -445,17 +335,19 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
             onStateChanged();
         }
 
-        String oldBehaviorLeaderId = oldBehavior == null ? null : oldBehaviorState.getLeaderId();
+        String lastValidLeaderId = oldBehavior == null ? null : oldBehaviorState.getLastValidLeaderId();
         String oldBehaviorStateName = oldBehavior == null ? null : oldBehavior.state().name();
 
         // it can happen that the state has not changed but the leader has changed.
         Optional<ActorRef> roleChangeNotifier = getRoleChangeNotifier();
-        if(!Objects.equal(oldBehaviorLeaderId, currentBehavior.getLeaderId())) {
+        if(!Objects.equal(lastValidLeaderId, currentBehavior.getLeaderId()) ||
+           oldBehaviorState.getLeaderPayloadVersion() != currentBehavior.getLeaderPayloadVersion()) {
             if(roleChangeNotifier.isPresent()) {
-                roleChangeNotifier.get().tell(new LeaderStateChanged(getId(), currentBehavior.getLeaderId()), getSelf());
+                roleChangeNotifier.get().tell(newLeaderStateChanged(getId(), currentBehavior.getLeaderId(),
+                        currentBehavior.getLeaderPayloadVersion()), getSelf());
             }
 
-            onLeaderChanged(oldBehaviorLeaderId, currentBehavior.getLeaderId());
+            onLeaderChanged(lastValidLeaderId, currentBehavior.getLeaderId());
         }
 
         if (roleChangeNotifier.isPresent() &&
@@ -465,6 +357,20 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         }
     }
 
+    protected LeaderStateChanged newLeaderStateChanged(String memberId, String leaderId, short leaderPayloadVersion) {
+        return new LeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
+    }
+
+    @Override
+    public long snapshotSequenceNr() {
+        // When we do a snapshot capture, we also capture and save the sequence-number of the persistent journal,
+        // so that we can delete the persistent journal based on the saved sequence-number
+        // However , when akka replays the journal during recovery, it replays it from the sequence number when the snapshot
+        // was saved and not the number we saved.
+        // We would want to override it , by asking akka to use the last-sequence number known to us.
+        return context.getSnapshotManager().getLastSequenceNumber();
+    }
+
     /**
      * When a derived RaftActor needs to persist something it must call
      * persistData.
@@ -488,22 +394,22 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
 
         replicatedLog().appendAndPersist(replicatedLogEntry, new Procedure<ReplicatedLogEntry>() {
             @Override
-            public void apply(ReplicatedLogEntry replicatedLogEntry) throws Exception {
-                if(!hasFollowers()){
+            public void apply(ReplicatedLogEntry replicatedLogEntry) {
+                if (!hasFollowers()){
                     // Increment the Commit Index and the Last Applied values
                     raftContext.setCommitIndex(replicatedLogEntry.getIndex());
                     raftContext.setLastApplied(replicatedLogEntry.getIndex());
 
-                    // Apply the state immediately
-                    applyState(clientActor, identifier, data);
+                    // Apply the state immediately.
+                    self().tell(new ApplyState(clientActor, identifier, replicatedLogEntry), self());
 
                     // Send a ApplyJournalEntries message so that we write the fact that we applied
                     // the state to durable storage
                     self().tell(new ApplyJournalEntries(replicatedLogEntry.getIndex()), self());
 
-                    context.getSnapshotManager().trimLog(context.getLastApplied(), currentBehavior);
-
                 } else if (clientActor != null) {
+                    context.getReplicatedLog().captureSnapshotIfReady(replicatedLogEntry);
+
                     // Send message for replication
                     currentBehavior.handleMessage(getSelf(),
                             new Replicate(clientActor, identifier, replicatedLogEntry));
@@ -589,7 +495,20 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
     }
 
     protected void updateConfigParams(ConfigParams configParams) {
+
+        // obtain the RaftPolicy for oldConfigParams and the updated one.
+        String oldRaftPolicy = context.getConfigParams().
+            getCustomRaftPolicyImplementationClass();
+        String newRaftPolicy = configParams.
+            getCustomRaftPolicyImplementationClass();
+
+        LOG.debug ("RaftPolicy used with prev.config {}, RaftPolicy used with newConfig {}",
+            oldRaftPolicy, newRaftPolicy);
         context.setConfigParams(configParams);
+        if (!Objects.equal(oldRaftPolicy, newRaftPolicy)) {
+            //RaftPolicy is modifed for the Actor. Re-initialize its current behaviour
+            initializeBehavior();
+        }
     }
 
     public final DataPersistenceProvider persistence() {
@@ -621,7 +540,7 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
                     // Make saving Snapshot successful
                     // Committing the snapshot here would end up calling commit in the creating state which would
                     // be a state violation. That's why now we send a message to commit the snapshot.
-                    self().tell(COMMIT_SNAPSHOT, self());
+                    self().tell(RaftActorSnapshotMessageSupport.COMMIT_SNAPSHOT, self());
                 }
             });
         }
@@ -645,10 +564,6 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         context.setPeerAddress(peerId, peerAddress);
     }
 
-    protected void commitSnapshot(long sequenceNumber) {
-        context.getSnapshotManager().commit(persistence(), sequenceNumber);
-    }
-
     /**
      * The applyState method will be called by the RaftActor when some data
      * needs to be applied to the actor's state
@@ -670,31 +585,10 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         Object data);
 
     /**
-     * This method is called during recovery at the start of a batch of state entries. Derived
-     * classes should perform any initialization needed to start a batch.
-     */
-    protected abstract void startLogRecoveryBatch(int maxBatchSize);
-
-    /**
-     * This method is called during recovery to append state data to the current batch. This method
-     * is called 1 or more times after {@link #startLogRecoveryBatch}.
-     *
-     * @param data the state data
-     */
-    protected abstract void appendRecoveredLogEntry(Payload data);
-
-    /**
-     * This method is called during recovery to reconstruct the state of the actor.
-     *
-     * @param snapshotBytes A snapshot of the state of the actor
-     */
-    protected abstract void applyRecoverySnapshot(byte[] snapshotBytes);
-
-    /**
-     * This method is called during recovery at the end of a batch to apply the current batched
-     * log entries. This method is called after {@link #appendRecoveredLogEntry}.
+     * Returns the RaftActorRecoveryCohort to participate in persistence recovery.
      */
-    protected abstract void applyCurrentLogRecoveryBatch();
+    @Nonnull
+    protected abstract RaftActorRecoveryCohort getRaftActorRecoveryCohort();
 
     /**
      * This method is called when recovery is complete.
@@ -702,24 +596,10 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
     protected abstract void onRecoveryComplete();
 
     /**
-     * This method will be called by the RaftActor when a snapshot needs to be
-     * created. The derived actor should respond with its current state.
-     * <p/>
-     * During recovery the state that is returned by the derived actor will
-     * be passed back to it by calling the applySnapshot  method
-     *
-     * @return The current state of the actor
-     */
-    protected abstract void createSnapshot();
-
-    /**
-     * This method can be called at any other point during normal
-     * operations when the derived actor is out of sync with it's peers
-     * and the only way to bring it in sync is by applying a snapshot
-     *
-     * @param snapshotBytes A snapshot of the state of the actor
+     * Returns the RaftActorSnapshotCohort to participate in persistence recovery.
      */
-    protected abstract void applySnapshot(byte[] snapshotBytes);
+    @Nonnull
+    protected abstract RaftActorSnapshotCohort getRaftActorSnapshotCohort();
 
     /**
      * This method will be called by the RaftActor when the state of the
@@ -753,18 +633,30 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         return peerAddress;
     }
 
-    private void handleCaptureSnapshotReply(byte[] snapshotBytes) {
-        LOG.debug("{}: CaptureSnapshotReply received by actor: snapshot size {}", persistenceId(), snapshotBytes.length);
-
-        context.getSnapshotManager().persist(persistence(), snapshotBytes, currentBehavior, context.getTotalMemory());
-    }
-
     protected boolean hasFollowers(){
         return getRaftActorContext().hasFollowers();
     }
 
+    private void captureSnapshot() {
+        SnapshotManager snapshotManager = context.getSnapshotManager();
+
+        if(!snapshotManager.isCapturing()) {
+            LOG.debug("Take a snapshot of current state. lastReplicatedLog is {} and replicatedToAllIndex is {}",
+                replicatedLog().last(), currentBehavior.getReplicatedToAllIndex());
+
+            snapshotManager.capture(replicatedLog().last(), currentBehavior.getReplicatedToAllIndex());
+        }
+    }
+
+    /**
+     * @deprecated Deprecated in favor of {@link org.opendaylight.controller.cluster.raft.base.messages.DeleteEntries}
+     *             whose type for fromIndex is long instead of int. This class was kept for backwards
+     *             compatibility with Helium.
+     */
+    // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
+    @SuppressWarnings("serial")
+    @Deprecated
     static class DeleteEntries implements Serializable {
-        private static final long serialVersionUID = 1L;
         private final int fromIndex;
 
         public DeleteEntries(int fromIndex) {
@@ -776,8 +668,14 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         }
     }
 
+    /**
+     * @deprecated Deprecated in favor of non-inner class {@link org.opendaylight.controller.cluster.raft.base.messages.UpdateElectionTerm}
+     *             which has serialVersionUID set. This class was kept for backwards compatibility with Helium.
+     */
+    // Suppressing this warning as we can't set serialVersionUID to maintain backwards compatibility.
+    @SuppressWarnings("serial")
+    @Deprecated
     static class UpdateElectionTerm implements Serializable {
-        private static final long serialVersionUID = 1L;
         private final long currentTerm;
         private final String votedFor;
 
@@ -795,29 +693,50 @@ public abstract class RaftActor extends AbstractUntypedPersistentActor {
         }
     }
 
-    private class CreateSnapshotProcedure implements Procedure<Void> {
-
-        @Override
-        public void apply(Void aVoid) throws Exception {
-            createSnapshot();
-        }
-    }
-
     private static class BehaviorStateHolder {
         private RaftActorBehavior behavior;
-        private String leaderId;
+        private String lastValidLeaderId;
+        private short leaderPayloadVersion;
 
         void init(RaftActorBehavior behavior) {
             this.behavior = behavior;
-            this.leaderId = behavior != null ? behavior.getLeaderId() : null;
+            this.leaderPayloadVersion = behavior != null ? behavior.getLeaderPayloadVersion() : -1;
+
+            String behaviorLeaderId = behavior != null ? behavior.getLeaderId() : null;
+            if(behaviorLeaderId != null) {
+                this.lastValidLeaderId = behaviorLeaderId;
+            }
         }
 
         RaftActorBehavior getBehavior() {
             return behavior;
         }
 
-        String getLeaderId() {
-            return leaderId;
+        String getLastValidLeaderId() {
+            return lastValidLeaderId;
+        }
+
+        short getLeaderPayloadVersion() {
+            return leaderPayloadVersion;
+        }
+    }
+
+    private class SwitchBehaviorSupplier implements Supplier<RaftActorBehavior> {
+        private Object message;
+        private ActorRef sender;
+
+        public SwitchBehaviorSupplier handleMessage(ActorRef sender, Object message){
+            this.sender = sender;
+            this.message = message;
+            return this;
+        }
+
+        @Override
+        public RaftActorBehavior get() {
+            if(this.message instanceof SwitchBehavior){
+                return ((SwitchBehavior) message).getNewState().createBehavior(getRaftActorContext());
+            }
+            return currentBehavior.handleMessage(sender, message);
         }
     }
 }